Generation of white light closer to daylight with good color-rendering index properties can be achieved with the proper combination of emissions from the phosphor system consisting of semiconductor diode and Ce3+/Gd3+-doped yttrium aluminum garnet (YAG: Ce, Gd). Here, we report crystal structure and luminescent properties of Tb3+-substituted YAG: Ce, Gd. The values of lattice constant increases and the photoluminescent spectrum shows red emission shift, as the Tb3+ content increases in YAG. We also studied luminescent properties of these phosphors using vacuum ultraviolet excitation for future plasma display panel applications. We propose a possible mechanism for the energy migration from YAG host to Tb3+ and Ce3+ ions. © 2005 The Electrochemical Society. All rights reserved.